1. Field of the Invention
Embodiments of the invention generally relate to an optical connector assembly and method of fabricating the same, suitable for use in harsh environments such as down hole gas and oil well applications.
2. Background of the Related Art
Transmitting information, such as temperature, strain and seismic movement, through optical fibers utilized in down hole gas and oil (e.g., petroleum) field drilling applications is becoming more widely accepted as gas and oil field producers embrace the advantages of optical fiber systems over conventional metallic conductors. For example, optical fiber sensing systems exhibit increased long-term reliability over conventional conductors, often having a useful service life up to and exceeding four times the service life of conventional sensing systems utilizing metallic conductors, thus allowing efficient petroleum removal to continue long into the life of wells utilizing optical sensing systems, and thereby maximizing the profitability of older wells.
However, as optical fiber sensing systems for oil and gas well use become more widespread, it has become apparent that conventional optical equipment commonly utilized in above-ground telephone and data transmission is not compatible with the harsh environmental conditions present in down hole oil and gas well applications. For example, optical connector assemblies utilized in down hole sensing applications must be able to operate reliably in conditions that may include temperatures in excess of 300 degrees Celsius, static pressures in excess of 20,000 pounds per square inch (psi), vibration, corrosive chemistry and the presence of high partial pressures of hydrogen. Experience has demonstrated that conventional optical connector assemblies that utilize ceramic ferrules fastened to optical fiber by epoxy do not provide reliable and robust coupling of optical fibers at the elevated temperatures present in down hole well environments. Particularly, the mismatch in the thermal coefficient of expansion between the epoxy, the ceramic ferrules and the optical fiber results in movement and misalignment of the mating optical fibers in the connector assembly at high temperatures, causing an increase in optical loss and instability of the optical connection.
Therefore, there is a need for an improved method and apparatus for coupling optical fibers suitable for use in harsh environments.